Faster than a speeding atom: breakthrough to revolutionise computing

Australian scientists have developed a breakthrough technique to read information stored on single atoms that will significantly improve the accuracy of future quantum computers.

The University of NSW-led team is the first in the world to use light combined with electrical signals to detect and read information stored on single atoms - the atomic structures that will form the basic storage and processing units of super-powerful quantum computers.

''This is a revolutionary new technique, and people had doubts it was possible,'' said research leader Sven Rogge.

Quantum computers hold the promise of performing calculations billions of times faster than today's computers. While conventional computers store information as bits, a collection of ones and zeroes, quantum computers will use the bizarre properties of quantum physics to write and read information onto atoms and electrons, known as qubits.

Professor Rogge and his colleagues' technique is a first step towards developing quantum computers that can communicate with each other over long distances - the holy grail of quantum science.

Their results are published in the journal Nature.

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A qubit encodes information onto an atom using its magnetic field, known as its spin, which can be oriented in different directions using electromagnetic radiation.

Atoms can exist in many orientations, or states, at one time. This makes the processing speed and power of qubits far greater than traditional bits.

To produce a functioning qubit, scientists must be able to control an atom's spin state and then detect or ''read'' it. Professor Rogge and his colleagues' new technique used light to detect a single atom of erbium embedded in a silicon scaffold. They were then able to read the atom's orientation because it gave off an electrical signal that switched on a tiny transistor.

By shining a laser on the device, they could locate many atoms without knowing their exact positions, while reading the atoms' state via an electrical signal was more efficient and accurate.

''We have the best of both world with our combination of an electrical and optical system'', said co-author Matthew Sellars from the Australian National University.

The study's lead author, Chunming Yin, said the team hoped to use their new technique to couple multiple qubits using light.

''Ultimately this will lead to quantum communications over long distances,'' Dr Yin said.

The team, which also included researchers from the University of Melbourne, achieved their advance by shooting atoms of erbium, a rare earth metal often used in communications, into a silicon transistor using a machine known as an ion implanter.

While quantum computers are still a decade away, they will be able to perform computations, such as fast database searches and complex modelling, currently impossible for today's computers.

Last month, the teams' colleagues in the UNSW engineering department announced they could read and write information on an even smaller atomic structure than an atom, its nucleus.